Solve for $x$ : $7\sqrt{x} - 1 = 9\sqrt{x} + 7$
Subtract $7\sqrt{x}$ from both sides: $(7\sqrt{x} - 1) - 7\sqrt{x} = (9\sqrt{x} + 7) - 7\sqrt{x}$ $-1 = 2\sqrt{x} + 7$ Subtract $7$ from both sides: $-1 - 7 = (2\sqrt{x} + 7) - 7$ $-8 = 2\sqrt{x}$ Divide both sides by $2$ $\frac{-8}{2} = \frac{2\sqrt{x}}{2}$ Simplify. $-4 = \sqrt{x}$ The principal root of a number cannot be negative. So, there is no solution.